当我尝试使用 pyinstaller 时它声称它没有安装，当我尝试安装它时它声称它已经安装？

Question

So the title explains it all.

C:\Users\username>py -m pip install  pyinstaller
Requirement already satisfied: pyinstaller in c:\users\username\appdata\roaming\python\python37\site-packages (3.5)
Requirement already satisfied: altgraph in c:\users\username\appdata\roaming\python\python37\site-packages (from pyinstaller) (0.16.1)
Requirement already satisfied: pefile>=2017.8.1 in c:\users\username\appdata\roaming\python\python37\site-packages (from pyinstaller) (2019.4.18)
Requirement already satisfied: setuptools in c:\program files (x86)\microsoft visual studio\shared\python37_64\lib\site-packages (from pyinstaller) (40.8.0)
Requirement already satisfied: pywin32-ctypes>=0.2.0 in c:\users\username\appdata\roaming\python\python37\site-packages (from pyinstaller) (0.2.0)
Requirement already satisfied: future in c:\users\username\appdata\roaming\python\python37\site-packages (from pefile>=2017.8.1->pyinstaller) (0.18.2)

C:\Users\username>py -m pyinstaller
C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\python.exe: No module named pyinstaller

NOTES: I use py instead of python because python doesn't work for an unknown reason

C:\Users\username>python
'python' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\username>py
Python 3.7.4 (tags/v3.7.4:e09359112e, Jul  8 2019, 20:34:20) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

Invoking just "pyinstaller" doesn't work neither it does for pip

C:\Users\username>pip
'pip' is not recognized as an internal or external command,
operable program or batch file.

C:\Users\username>py -m pip

Usage:
  C:\Program Files (x86)\Microsoft Visual Studio\Shared\Python37_64\python.exe -m pip <command> [options]
(...)

C:\Users\username>pyinstaller
'pyinstaller' is not recognized as an internal or external command,
operable program or batch file.

I'd like to know why these things work differently for other people as well.

Answer 1

Read those instruction from main page https://pyinstaller.readthedocs.io/en/stable/installation.html

Try install by pip install pyinstaller . if leads to numpy error then downgrade the pyinstaller version to 3.4 by pip install pyinstaller==3.4

Answer 2

If anyone else has the same problem the solution of installing different version works. After that you can do pip install --upgrade pyinstaller and it will be up-to-date and working, no idea why...